JP2015125150A - Image-capturing lens and image-capturing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image-capturing lens which is at low costs and yet has high optical performance with its chromatic aberration excellently corrected, and an image-capturing device equipped with this image-capturing lens.SOLUTION: An image-capturing lens 1 comprises, in order from an object side, a negative first lens L1, a positive second lens L2, a negative third lens L3, a positive fourth lens L4, a positive fifth lens L5, and a negative sixth lens L6. When the refractive indexes of the third lens L3 to the sixth lens L6 are assumed to Nd3 to Nd6, respectively, conditional expressions (1):Nd3<1.7, (2):Nd4<1.6, (3):Nd5<1.6, and (4):Nd6<1.89 are satisfied.

Description

  The present invention relates to an imaging lens and an imaging apparatus, and more particularly, to an in-vehicle camera, a mobile terminal camera, a surveillance camera, and the like using an imaging element such as a charge coupled device (CCD) or a complementary metal oxide semiconductor (CMOS). The present invention relates to an imaging lens suitable for the imaging, and an imaging device including the imaging lens.

  In recent years, image sensors such as CCDs and CMOSs have been greatly reduced in size and pixels. At the same time, an image pickup apparatus body including these image pickup elements is also downsized, and an image pickup lens mounted thereon is required to be downsized in addition to good optical performance. On the other hand, in applications such as in-vehicle cameras and surveillance cameras, it is required to be compact and can be configured at low cost, and to have a wide angle and high performance.

  In Patent Document 1 below, as an imaging lens mounted on a vehicle-mounted camera, a six-lens lens system in which a negative lens, a positive lens, a negative lens, a positive lens, a positive lens, and a negative lens are arranged in order from the object side. Is described. Patent Document 2 below describes an image reading lens having a six-lens configuration having the same refractive power (hereinafter also referred to as power) array as described above.

International Publication WO2012 / 086199A1 JP 2009-204997 A

  By the way, demands for lenses mounted on in-vehicle cameras and surveillance cameras are becoming stricter year by year, and further cost reduction and high performance are desired. Especially, both cost reduction and good chromatic aberration correction are compatible. It is hoped that

  SUMMARY OF THE INVENTION In view of the above circumstances, an object of the present invention is to provide an imaging lens having a high optical performance with a low chromatic aberration corrected at a low cost, and an imaging apparatus including the imaging lens.

The imaging lens of the present invention has, in order from the object side, a first lens having a negative refractive power, a second lens having a positive refractive power, a third lens having a negative refractive power, and a positive refractive power. The fourth lens includes a sixth lens having a positive refractive power, a sixth lens having a negative refractive power, and a sixth lens having a negative refractive power, and satisfies the following conditional expression. .
Nd3 <1.7 (1)
Nd4 <1.6 (2)
Nd5 <1.6 (3)
Nd6 <1.89 (4)
However,
Nd3: Refractive index of the third lens material for the d-line Nd4: Refractive index of the fourth lens material for the d-line Nd5: Refractive index of the fifth lens material for the d-line Nd6: Refractive index of the sixth lens material for the d-line Refractive index

In the imaging lens of the present invention, it is preferable that the following conditional expressions (5) to (21) are satisfied. As a preferable embodiment, any one of the following conditional expressions (5) to (21) may be satisfied, or any two or more combinations may be satisfied.
1.0 <(R1f + R1r) / (R1f−R1r) (5)
0.3 <f4 / f5 (6)
f5 / f <3.4 (7)
0.3 <f56 / f (8)
0.17 <Db23 / f (9)
0.0 <R1f / f (10)
−3.0 <f1 / f <−0.5 (11)
−0.15 <(R2f + R2r) / (R2f−R2r) (12)
0.1 <f12 / f <4.0 (13)
0.5 <f4 / f <5.0 (14)
0.1 <f12 / f3456 <2.0 (15)
−3.0 <(R5f + R5r) / (R5f−R5r) <− 0.1 (16)
0.2 <f2 / f <3.0 (17)
0.2 <(D3 + Db23) / f <3.0 (18)
−3.0 <f1 / f2 <−0.2 (19)
νd3 <30 (20)
0.2 <Db12 / f <3.0 (21)
However,
R1f: paraxial radius of curvature of object side surface of first lens R1r: paraxial radius of curvature of image side surface of first lens R2f: paraxial radius of curvature of object side surface of second lens R2r: second lens Paraxial radius of curvature R5f of the image side surface of the fifth lens: Paraxial radius of curvature R5r of the object side surface of the fifth lens: Paraxial radius of curvature D3 of the image side surface of the fifth lens D3: Center thickness Db12 of the second lens: Air distance Db23 on the optical axis of the first lens and the second lens: Air distance on the optical axis of the second lens and the third lens f: Focal length f1 of the entire system f1: Focal length f2 of the first lens: Second lens Focal length f4: focal length of fourth lens f5: focal length of fifth lens f12: combined focal length of first lens and second lens f56: combined focal length of fifth lens and sixth lens f3456: third lens Focal length νd3 from the first lens to the sixth lens: Abbe number with respect to the d-line of quality

  In the imaging lens of the present invention, it is preferable that the fourth lens is a biconvex lens.

  In the present invention, the sign of refractive power (power) and the uneven shape of the surface are considered in the paraxial region unless otherwise specified. In the present invention, the sign of the radius of curvature is positive when the convex shape is directed toward the object side and negative when the convex shape is directed toward the image side.

  Note that “substantially” in the above “consisting essentially of six lenses composed of” means that the imaging lens of the present invention has substantially power other than the six lenses. It is intended that an optical element other than a lens such as a lens, an aperture, a cover glass or a filter, a lens flange, a lens barrel, a mechanism portion such as a camera shake correction mechanism, or the like may be included.

  The imaging device of the present invention includes the imaging lens of the present invention described above.

  According to the imaging lens of the present invention, in the six-lens system, the power array is suitably set and the predetermined conditional expression is satisfied, so that the chromatic aberration is corrected well at a low cost. In addition, a lens system having high optical performance can be realized.

  According to the imaging apparatus of the present invention, since the imaging lens of the present invention is provided, it can be configured at low cost and a good image can be acquired.

The figure which shows the structure and optical path of the imaging lens concerning one Embodiment of this invention. Sectional drawing which shows the lens structure of the imaging lens of Example 1 of this invention. Sectional drawing which shows the lens structure of the imaging lens of Example 2 of this invention. Sectional drawing which shows the lens structure of the imaging lens of Example 3 of this invention. Sectional drawing which shows the lens structure of the imaging lens of Example 4 of this invention. Sectional drawing which shows the lens structure of the imaging lens of Example 5 of this invention. Sectional drawing which shows the lens structure of the imaging lens of Example 6 of this invention. Sectional drawing which shows the lens structure of the imaging lens of Example 7 of this invention. Sectional drawing which shows the lens structure of the imaging lens of Example 8 of this invention. Sectional drawing which shows the lens structure of the imaging lens of Example 9 of this invention. Sectional drawing which shows the lens structure of the imaging lens of Example 10 of this invention. Sectional drawing which shows the lens structure of the imaging lens of Example 11 of this invention. Sectional drawing which shows the lens structure of the imaging lens of Example 12 of this invention. Sectional drawing which shows the lens structure of the imaging lens of Example 13 of this invention. Sectional drawing which shows the lens structure of the imaging lens of Example 14 of this invention. Sectional drawing which shows the lens structure of the imaging lens of Example 15 of this invention. Sectional drawing which shows the lens structure of the imaging lens of Example 16 of this invention. Sectional drawing which shows the lens structure of the imaging lens of Example 17 of this invention. Sectional drawing which shows the lens structure of the imaging lens of Example 18 of this invention. Sectional drawing which shows the lens structure of the imaging lens of Example 19 of this invention. Sectional drawing which shows the lens structure of the imaging lens of Example 20 of this invention. FIG. 2 is a diagram illustrating various aberrations of the imaging lens according to the first embodiment of the present invention. From the left side of the drawing, spherical aberration diagram, astigmatism diagram, distortion diagram, and magnification chromatic aberration diagram. FIG. 6 is a diagram illustrating various aberrations of the imaging lens according to the second embodiment of the present invention. FIG. 6 is various aberration diagrams of the imaging lens of Example 3 according to the present invention. From the left side of the drawing, spherical aberration diagram, astigmatism diagram, distortion diagram, and magnification chromatic aberration diagram. FIG. 6 is various aberration diagrams of the imaging lens of Example 4 of the present invention. From the left side of the drawing, spherical aberration diagrams, astigmatism diagrams, distortion diagrams, and magnification chromatic aberration diagrams. FIG. 10 is a diagram illustrating all aberrations of the imaging lens according to Example 5 of the present invention. From the left side of the drawing, spherical aberration diagram, astigmatism diagram, distortion diagram, and magnification chromatic aberration diagram. FIG. 9A is a diagram illustrating all aberrations of the imaging lens according to Example 6 of the present invention. From the left side of the drawing, spherical aberration diagram, astigmatism diagram, distortion diagram, and chromatic aberration diagram of magnification. FIG. 9A is a diagram illustrating all aberrations of the imaging lens according to Example 7 of the present invention. From the left side of the drawing, spherical aberration diagram, astigmatism diagram, distortion diagram, and magnification chromatic aberration diagram. FIG. 10 is various aberration diagrams of the imaging lens of Example 8 of the present invention. From the left side of the drawing, spherical aberration diagram, astigmatism diagram, distortion diagram, and magnification chromatic aberration diagram. FIG. 9A is a diagram illustrating all aberrations of the imaging lens according to Example 9 of the present invention. From the left side of the drawing, spherical aberration diagram, astigmatism diagram, distortion diagram, and chromatic aberration diagram of magnification. FIG. 14 is a diagram illustrating all aberrations of the imaging lens according to Example 10 of the present invention. From the left side of the drawing, spherical aberration diagram, astigmatism diagram, distortion diagram, and magnification chromatic aberration diagram. FIG. 14A is a diagram illustrating all aberrations of the imaging lens according to Example 11 of the present invention. From the left side of the drawing, spherical aberration diagram, astigmatism diagram, distortion diagram, and magnification chromatic aberration diagram. FIG. 14 is a diagram illustrating all aberrations of the imaging lens according to Example 12 of the present invention. From the left side of the drawing, spherical aberration diagram, astigmatism diagram, distortion diagram, and magnification chromatic aberration diagram. FIG. 14A is a diagram illustrating all aberrations of the imaging lens according to Example 13 of the present invention. From the left side of the drawing, spherical aberration diagram, astigmatism diagram, distortion diagram, and chromatic aberration diagram of magnification. FIG. 14 is a diagram illustrating all aberrations of the imaging lens according to Example 14 of the present invention. From the left side of the drawing, spherical aberration diagram, astigmatism diagram, distortion diagram, and magnification chromatic aberration diagram. FIG. 16 is a diagram illustrating all aberrations of the imaging lens according to Example 15 of the present invention. From the left side of the drawing, spherical aberration diagram, astigmatism diagram, distortion diagram, and magnification chromatic aberration diagram. FIG. 18 is a diagram illustrating all aberrations of the imaging lens according to Example 16 of the present invention. From the left side of the drawing, spherical aberration diagram, astigmatism diagram, distortion diagram, and magnification chromatic aberration diagram. FIG. 19A is a diagram illustrating all aberrations of the image pickup lens according to Example 17 of the present invention. From the left side of the drawing, spherical aberration diagram, astigmatism diagram, distortion diagram, and magnification chromatic aberration diagram. FIG. 18A is a diagram illustrating all aberrations of the imaging lens according to Example 18 of the present invention. From the left side of the drawing, spherical aberration diagram, astigmatism diagram, distortion diagram, and magnification chromatic aberration diagram. FIG. 19A is a diagram illustrating all aberrations of the imaging lens according to Example 19 of the present invention. From the left side of the drawing, spherical aberration diagram, astigmatism diagram, distortion diagram, and magnification chromatic aberration diagram. FIG. 19 is a diagram illustrating all aberrations of the imaging lens according to Example 20 of the present invention. From the left side of the drawing, spherical aberration diagram, astigmatism diagram, distortion diagram, and magnification chromatic aberration diagram. The figure for demonstrating arrangement | positioning of the vehicle-mounted imaging device concerning embodiment of this invention

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

Embodiment of imaging lens
First, an imaging lens according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a diagram illustrating a configuration and an optical path of an imaging lens 1 according to an embodiment of the present invention. The imaging lens 1 shown in FIG. 1 corresponds to an imaging lens according to Example 1 of the present invention described later. In FIG. 1, the left side of the drawing is the object side, the right side is the image side, and the axial beam 2 from an object point at an infinite distance and off-axis beams 3 and 4 with respect to the maximum total field angle are also shown. .

  In FIG. 1, the imaging element 5 disposed on the image plane Sim including the image point Pim of the imaging lens 1 is also illustrated in consideration of the case where the imaging lens 1 is applied to the imaging apparatus. The imaging device 5 converts an optical image formed by the imaging lens 1 into an electrical signal, and for example, a CCD image sensor or a CMOS image sensor can be used.

  When the imaging lens 1 is applied to an imaging apparatus, it is preferable to provide a cover glass, a low-pass filter, an infrared cut filter, or the like according to the configuration on the camera side on which the lens is mounted. An example is shown in which an assumed parallel plate-shaped optical member PP is disposed between the lens closest to the image side and the imaging element 5 (image plane Sim).

  The imaging lens 1 includes, in order from the object side, a first lens L1 having a negative refractive power, a second lens L2 having a positive refractive power, a third lens L3 having a negative refractive power, and a positive refractive power. Are substantially composed of six lenses including a fourth lens L4 having a positive refractive power, a fifth lens L5 having a positive refractive power, and a sixth lens L6 having a negative refractive power. Although the aperture stop St is also illustrated in FIG. 1, the illustrated aperture stop St does not indicate the shape or size, but indicates the position on the optical axis Z.

  Disposing the first negative lens L1 closest to the object side is advantageous for widening the angle. By using the third lens L3 and the fourth lens L4 as a negative lens and a positive lens, respectively, it is advantageous for good correction of axial chromatic aberration. By using the fifth lens L5 and the sixth lens L6 as a positive lens and a negative lens, respectively, it is advantageous for good correction of chromatic aberration of magnification. By using negative, positive, negative, positive, positive, and negative power arrays in order from the object side, it is advantageous for realizing a small F number, a wide angle of view, and good resolution performance.

The imaging lens 1 is configured to satisfy the following conditional expressions (1) to (4).
Nd3 <1.7 (1)
Nd4 <1.6 (2)
Nd5 <1.6 (3)
Nd6 <1.89 (4)
However,
Nd3: Refractive index of the third lens material for the d-line Nd4: Refractive index of the fourth lens material for the d-line Nd5: Refractive index of the fifth lens material for the d-line Nd6: Refractive index of the sixth lens material for the d-line Refractive index

  By satisfying conditional expression (1), the refractive index of the material of the third lens L3 with respect to the d-line can be lowered, and the cost of the third lens L3 can be easily suppressed.

  By satisfying the conditional expression (2), the refractive index of the material of the fourth lens L4 with respect to the d-line can be lowered, and the cost of the fourth lens L4 can be easily suppressed, and the fourth lens L4 can be reduced. It becomes easy to increase the Abbe number, and it becomes easy to correct axial chromatic aberration and lateral chromatic aberration.

  By satisfying conditional expression (3), the refractive index of the material of the fifth lens L5 with respect to the d-line can be lowered, and the cost of the fifth lens L5 can be easily reduced. It becomes easy to increase the Abbe number, and it becomes easy to correct axial chromatic aberration and lateral chromatic aberration.

  By satisfying conditional expression (4), the refractive index of the material of the sixth lens L6 with respect to the d-line can be made relatively low, and the cost of the sixth lens L6 can be easily suppressed.

The imaging lens 1 preferably satisfies any one or any combination of the following conditional expressions (5) to (24).
1.0 <(R1f + R1r) / (R1f−R1r) (5)
0.3 <f4 / f5 (6)
f5 / f <3.4 (7)
0.3 <f56 / f (8)
0.17 <Db23 / f (9)
0.0 <R1f / f (10)
−3.0 <f1 / f <−0.5 (11)
−0.15 <(R2f + R2r) / (R2f−R2r) (12)
0.1 <f12 / f <4.0 (13)
0.5 <f4 / f <5.0 (14)
0.1 <f12 / f3456 <2.0 (15)
−3.0 <(R5f + R5r) / (R5f−R5r) <− 0.1 (16)
0.2 <f2 / f <3.0 (17)
0.2 <(D3 + Db23) / f <3.0 (18)
−3.0 <f1 / f2 <−0.2 (19)
νd3 <30 (20)
0.2 <Db12 / f <3.0 (21)
1.0 <(Db12 + D3) / f (22)
1.6 <f3456 / f (23)
−4.0 <(R6f + R6r) / (R6f−R6r) (24)
However,
R1f: paraxial radius of curvature of object side surface of first lens R1r: paraxial radius of curvature of image side surface of first lens R2f: paraxial radius of curvature of object side surface of second lens R2r: second lens The paraxial radius of curvature R5f of the image side surface of the fifth lens: The paraxial radius of curvature R5r of the object side surface of the fifth lens: The paraxial radius of curvature R6f of the image side surface of the fifth lens: The object side surface of the sixth lens Paraxial radius of curvature R6r: Paraxial radius of curvature of the image side surface of the sixth lens D3: Center thickness of the second lens Db12: Air spacing on the optical axis of the first lens and the second lens Db23: Second lens Air spacing on the optical axis of the third lens f: focal length f1 of the entire system f1: focal length f1 of the first lens f2: focal length of the second lens f4: focal length of the fourth lens f5: focal length of the fifth lens f12 : Synthetic focal length f56 of the first lens and the second lens f56: of the fifth lens and the sixth lens Forming focal F3456: Abbe number to the d-line of the material of the third lens: a third lens sixth composite focal distance to the lens νd3

  By configuring so as not to be less than or equal to the lower limit of conditional expression (5), the first lens L1, which is a negative lens, can be a meniscus lens having a convex surface facing the object side, and distortion can be easily corrected.

  By configuring so that it does not fall below the lower limit of conditional expression (6), it becomes easy to suppress the power of the fourth lens L4 from becoming too strong, or the power of the fifth lens L5 becomes too weak. It becomes easy to suppress, it becomes easy to prevent the power from being biased to either the fourth lens L4 or the fifth lens L5, and it becomes easy to satisfactorily correct spherical aberration.

  By configuring so as not to exceed the upper limit of conditional expression (7), it becomes easy to suppress the power of the fifth lens L5 from being weakened, and the fifth lens L5 and the sixth lens L6 cooperate to perform magnification. It becomes easy to correct the chromatic aberration of the lens, or it is easy to suppress an increase in the angle at which the peripheral rays are incident on the image pickup device 5, and shading can be easily suppressed.

  By configuring so that the lower limit of conditional expression (8) is not exceeded, it becomes easy to increase the combined focal length of the fifth lens L5 and the sixth lens L6 with a positive value, and to easily increase the back focus. It becomes.

  By configuring so as not to be less than or equal to the lower limit of conditional expression (9), it is easy to increase the air gap between the second lens L2 and the third lens L3, and it becomes easy to correct spherical aberration and astigmatism.

  By configuring so as not to be less than or equal to the lower limit of conditional expression (10), the object side surface of the first lens L1 can be a convex surface, and light rays are refracted greatly by the object side surface of the first lens L1. It becomes easy to suppress this, and distortion correction becomes easy.

  By configuring so as not to exceed the upper limit of conditional expression (11), it becomes easy to suppress the power of the first lens L1, and it becomes easy to correct curvature of field and distortion. By configuring so as not to be less than or equal to the lower limit of conditional expression (11), it becomes easy to secure the power of the first lens L1, and it is easy to widen the angle.

  By configuring so as not to be below the lower limit of conditional expression (12), it becomes easy to increase the absolute value of the radius of curvature of the object side surface of the second lens L2, and the distortion can be easily corrected.

  By configuring so as not to exceed the upper limit of conditional expression (13), it becomes easy to increase the combined refractive power of the first lens L1 and the second lens L2 with a positive value, and astigmatism can be corrected. It becomes easy. By configuring so that it does not fall below the lower limit of conditional expression (13), it becomes easy to suppress the combined refractive power of the first lens L1 and the second lens L2 to be a positive value and become too strong, and widening the angle. It becomes easy.

  By configuring so that the upper limit of conditional expression (14) is not exceeded, it becomes easy to increase the power of the fourth lens L4, and the third lens L3 and the fourth lens L4 cooperate to provide axial chromatic aberration. It becomes easy to suppress. By configuring so that the lower limit of conditional expression (14) is not reached, it becomes easy to suppress the power of the fourth lens L4, and it becomes easy to divide the positive power between the fourth lens L4 and the fifth lens. The spherical aberration can be easily corrected.

  By configuring so as not to exceed the upper limit of the conditional expression (15), it becomes easy to increase the combined power of the first lens L1 and the second lens L2, thereby reducing the size of the lens system and correcting astigmatism. It becomes easy, or it becomes easy to suppress the combined power of the third lens L3 to the sixth lens L6, and it becomes easy to lengthen the back focus. By configuring so that the lower limit of conditional expression (15) is not exceeded, it becomes easy to suppress the combined power of the first lens L1 and the second lens L2, and it becomes easy to widen the angle, or from the third lens L3. It becomes easy to increase the combined power of the sixth lens L6, and it becomes easy to correct spherical aberration and suppress an increase in the angle at which peripheral light rays enter the image sensor.

  By configuring so that the upper limit of conditional expression (16) is not exceeded, the fifth lens L5 may be a lens in which the absolute value of the radius of curvature of the object side surface is smaller than the absolute value of the radius of curvature of the image side surface. It becomes easy. This facilitates correction of spherical aberration and astigmatism. By configuring so as not to be less than or equal to the lower limit of conditional expression (16), it becomes easy to increase the difference between the curvature radius of the object-side surface and the curvature radius of the image-side surface in the fifth lens L5. Since it becomes easy to increase the power of the lens L5, it is easy to suppress an increase in the angle at which the peripheral rays are incident on the image sensor.

  By configuring so as not to exceed the upper limit of conditional expression (17), it becomes easy to increase the power of the second lens L2, and it becomes easy to correct astigmatism. By configuring so as not to be less than or equal to the lower limit of conditional expression (17), it is easy to suppress the power of the second lens L2 from becoming too strong, and the tolerance of manufacturing errors with respect to decentration can be increased. Cost reduction becomes easy.

  By configuring so that the upper limit of conditional expression (18) is not exceeded, the lens system can be easily downsized. By configuring so as not to be less than or equal to the lower limit of conditional expression (18), it becomes easy to increase the center thickness of the second lens L2 or increase the distance between the second lens L2 and the third lens L3. Correction of aberration and astigmatism becomes easy.

  By configuring so as not to exceed the upper limit of conditional expression (19), it becomes easy to suppress the power of the first lens L1, or it becomes easy to increase the power of the second lens L2, and spherical aberration, Astigmatism can be easily corrected. By configuring so as not to be less than or equal to the lower limit of conditional expression (19), it is easy to increase the power of the first lens L1, and it is easy to widen the angle.

  By configuring so as not to exceed the upper limit of conditional expression (20), it is easy to satisfactorily correct axial chromatic aberration.

  By configuring so as not to exceed the upper limit of conditional expression (21), it is easy to suppress an increase in the air gap between the first lens L1 and the second lens L2, and the lens system can be easily downsized. By configuring so as not to be less than the lower limit of conditional expression (21), it is easy to suppress the air space between the first lens L1 and the second lens L2 from becoming too small, and it is easy to correct astigmatism and distortion. It becomes.

  By configuring so as not to be below the lower limit of conditional expression (22), it becomes easy to increase the air gap between the first lens L1 and the second lens L2 and the center thickness of the second lens L2, and astigmatism and distortion. It becomes easy to correct.

  By configuring so as not to be less than or equal to the lower limit of conditional expression (23), it is easy to prevent the combined power of the third lens L3 to the fifth lens L5 from becoming too strong, and it is easy to increase the back focus. Become.

  By configuring so as not to be less than or equal to the lower limit of conditional expression (24), it becomes easy to suppress the power of the sixth lens L6 from becoming too weak, and it becomes easy to correct chromatic aberration of magnification.

  In addition, in order to enhance the above-described effects, for each of the above conditional expressions, the lower limit or the upper limit is changed as in the following changed value, the upper limit is further added as follows, or the lower limit is added. It is preferable to satisfy the above. Although the modified example of a preferable conditional expression is also described below as an example, it is not limited to what was described as a formula as a preferable aspect, It is comprised combining the lower limit change value and the upper limit change value which are described below. It may satisfy the conditional expression.

The upper limit change value of conditional expression (1) is preferably 1.68, and more preferably 1.65. A lower limit may be added to the conditional expression (1), and the lower limit is preferably set to 1.50. This makes it easy to increase the power of the third lens L3 and easily correct axial chromatic aberration. It becomes. Further, the lower limit change value added to the conditional expression (1) is preferably 1.55, and more preferably 1.58. From the above, it is more preferable to satisfy at least one of the following conditional expressions (1-1) to (1-4), for example.
Nd3 <1.68 (1-1)
1.50 <Nd3 <1.65 (1-2)
1.55 <Nd3 <1.68 (1-3)
1.58 <Nd3 <1.7 (1-4)

The upper limit change value of conditional expression (2) is preferably 1.58, and more preferably 1.55. A lower limit may be added to conditional expression (2), and the lower limit is preferably set to 1.45, which facilitates correction of field curvature. The lower limit change value added to conditional expression (2) is preferably 1.48, more preferably 1.49, and even more preferably 1.50. From the above, it is more preferable to satisfy at least one of the following conditional expressions (2-1) to (2-4), for example.
Nd4 <1.55 (2-1)
1.45 <Nd4 <1.6 (2-2)
1.48 <Nd4 <1.58 (2-3)
1.50 <Nd4 <1.58 (2-4)

The upper limit change value of conditional expression (3) is preferably 1.58, and more preferably 1.55. A lower limit may be added to conditional expression (3), and the lower limit is preferably 1.45. This makes it easy to increase the power of the fifth lens L5 and facilitate correction of field curvature. In other words, it is easy to suppress an increase in the angle at which peripheral rays are incident on the image sensor, and it is easy to suppress shading. The lower limit change value added to the conditional expression (3) is preferably 1.48, and more preferably 1.50. From the above, it is more preferable that at least one of the following conditional expressions (3-1) to (3-4) is satisfied, for example.
Nd5 <1.55 (3-1)
1.45 <Nd5 <1.6 (3-2)
1.48 <Nd5 <1.58 (3-3)
1.50 <Nd5 <1.58 (3-4)

The upper limit change value of conditional expression (4) is preferably 1.86, more preferably 1.70, even more preferably 1.68, and even more preferably 1.65. Even more preferable. A lower limit may be added to conditional expression (4), and the lower limit is preferably set to 1.50. This makes it easy to increase the power of the sixth lens L6 and facilitate correction of chromatic aberration of magnification. Become. The lower limit change value added to conditional expression (4) is preferably 1.55, and more preferably 1.58. From the above, it is more preferable to satisfy at least one of the following conditional expressions (4-1) to (4-4), for example.
Nd6 <1.86 (4-1)
1.50 <Nd6 <1.70 (4-2)
1.55 <Nd6 <1.68 (4-3)
1.58 <Nd6 <1.65 (4-4)

The lower limit change value of conditional expression (5) is preferably 1.1, and more preferably 1.2. An upper limit may be added to the conditional expression (5), and the upper limit is preferably set to 3.0, whereby the difference between the absolute values of the curvature radii of the object-side surface and the image-side surface of the first lens L1. Can be easily increased, and widening of the angle is facilitated. The upper limit change value added to the conditional expression (5) is more preferably 2.7, still more preferably 2.4, and still more preferably 2.2. From the above, it is more preferable to satisfy at least one of the following conditional expressions (5-1) to (5-4), for example.
1.2 <(R1f + R1r) / (R1f−R1r) (5-1)
1.1 <(R1f + R1r) / (R1f−R1r) <3.0 (5-2)
1.2 <(R1f + R1r) / (R1f−R1r) <2.7 (5-3)
1.2 <(R1f + R1r) / (R1f−R1r) <2.4 (5-4)

The change value of the lower limit of conditional expression (6) is preferably 0.4, more preferably 0.5, and even more preferably 0.6. An upper limit may be added to the conditional expression (6), and the upper limit is preferably set to 3.0, so that the power of the fifth lens L5 becomes too strong or the power of the fourth lens L4 becomes too weak. This makes it easy to prevent the power from being biased to either the fourth lens L4 or the fifth lens L5, and to easily correct spherical aberration. The upper limit change value added to the conditional expression (6) is more preferably 2.7, and even more preferably 2.4. From the above, it is more preferable to satisfy at least one of the following conditional expressions (6-1) to (6-4), for example.
0.4 <f4 / f5 (6-1)
0.3 <f4 / f5 <3.0 (6-2)
0.5 <f4 / f5 <2.7 (6-3)
0.6 <f4 / f5 <2.4 (6-4)

The change value of the upper limit of conditional expression (7) is preferably 3.2, more preferably 3.0, and even more preferably 2.8. A lower limit may be added to the conditional expression (7), and the lower limit is preferably set to 0.3. This makes it easy to prevent the power of the fifth lens L5 from becoming too strong, and increase the back focus. It is possible to increase the allowable amount of manufacturing error with respect to eccentricity, and it is easy to reduce the cost. The lower limit change value added to conditional expression (7) is more preferably 0.5, and more preferably 0.8. From the above, it is more preferable that at least one of the following conditional expressions (7-1) to (7-3) is satisfied, for example.
0.3 <f5 / f <3.4 (7-1)
0.5 <f5 / f <3.2 (7-2)
0.8 <f5 / f <3.0 (7-3)

The change value of the lower limit of conditional expression (8) is preferably 0.5, more preferably 1.0, and even more preferably 1.5. An upper limit may be added to conditional expression (8), and the upper limit is preferably set to 30, which makes it easy to increase the combined refractive power of the fifth lens L5 and the sixth lens L6. It becomes easy to suppress an increase in the angle at which the light beam enters the image sensor. The upper limit change value added to conditional expression (8) is preferably 25, more preferably 20, and even more preferably 15. From the above, it is more preferable that at least one of the following conditional expressions (8-1) to (8-4) is satisfied, for example.
0.3 <f56 / f <30 (8-1)
0.5 <f56 / f <25 (8-2)
1.0 <f56 / f <20 (8-3)
1.5 <f56 / f <15 (8-4)

The lower limit change value of conditional expression (9) is preferably 0.18, and more preferably 0.19. An upper limit may be added to conditional expression (9), and the upper limit is preferably set to 3.0, which makes it easy to prevent the air space between the second lens L2 and the third lens L3 from becoming too large. Thus, miniaturization is facilitated. The upper limit change value added to conditional expression (9) is preferably 2.5, more preferably 2.0, even more preferably 1.0, and 0.8. Even more preferred. From the above, it is more preferable to satisfy at least one of the following conditional expressions (9-1) to (9-3), for example.
0.17 <Db23 / f <3.0 (9-1)
0.18 <Db23 / f <2.0 (9-2)
0.19 <Db23 / f <1.0 (9-3)

The lower limit change value of conditional expression (10) is preferably 0.3. This makes it easy to suppress the radius of curvature of the object-side surface of the first lens L1 from becoming too small, making it easy to increase the power of the first lens L1, and facilitating widening of the angle. The change value of the lower limit of conditional expression (10) is more preferably 0.8, even more preferably 1.0, and even more preferably 1.5. An upper limit may be added to conditional expression (10), and the upper limit is preferably set to 30. Accordingly, it becomes easy to reduce the radius of curvature of the object side surface of the first lens L1, and distortion can be easily corrected. The upper limit change value added to the conditional expression (10) is more preferably 20, still more preferably 10, and still more preferably 7. From the above, it is more preferable to satisfy at least one of the following conditional expressions (10-1) to (10-4), for example.
0.0 <R1f / f <30 (10-1)
0.3 <R1f / f <20 (10-2)
0.8 <R1f / f <30 (10-3)
1.5 <R1f / f <10 (10-4)

The upper limit change value of conditional expression (11) is preferably −0.7, more preferably −0.8, and even more preferably −0.9. The lower limit change value of conditional expression (11) is preferably −2.8, more preferably −2.5, and even more preferably −2.0. From the above, it is more preferable that at least one of the following conditional expressions (11-1) to (11-3) is satisfied, for example.
−2.8 <f1 / f <−0.7 (11-1)
−2.5 <f1 / f <−0.8 (11-2)
−2.0 <f1 / f <−0.9 (11-3)

The lower limit change value of conditional expression (12) is preferably −0.10, more preferably −0.05, and still more preferably 0.00. An upper limit may be added to conditional expression (12), and the upper limit is preferably set to 0.9. As a result, it is easy to increase the power of the second lens L2, and it is easy to correct astigmatism. The upper limit change value added to conditional expression (12) is preferably 0.7, more preferably 0.5, and still more preferably 0.4. From the above, it is more preferable that at least one of the following conditional expressions (12-1) to (12-3) is satisfied, for example.
−0.15 <(R2f + R2r) / (R2f−R2r) <0.9 (12-1)
−0.10 <(R2f + R2r) / (R2f−R2r) <0.7 (12-2)
−0.05 <(R2f + R2r) / (R2f−R2r) <0.5 (12-3)

The upper limit change value of conditional expression (13) is preferably 3.0, more preferably 2.5, still more preferably 2.0, and even more preferably 1.8. Even more preferable. The change value of the lower limit of conditional expression (13) is preferably 0.5, more preferably 0.8, and even more preferably 1.0. From the above, it is more preferable to satisfy at least one of the following conditional expressions (13-1) to (13-3), for example.
0.5 <f12 / f <3.0 (13-1)
0.8 <f12 / f <2.5 (13-2)
1.0 <f12 / f <2.0 (13-3)

The change value of the upper limit of conditional expression (14) is preferably 3.0, more preferably 2.8, and even more preferably 2.6. The change value of the lower limit of conditional expression (14) is preferably 0.7, more preferably 0.9, and even more preferably 1.0. From the above, it is more preferable that at least one of the following conditional expressions (14-1) to (14-3) is satisfied, for example.
0.7 <f4 / f <3.0 (14-1)
0.9 <f4 / f <2.8 (14-2)
1.0 <f4 / f <2.6 (14-3)

The upper limit change value of conditional expression (15) is preferably 1.5, more preferably 1.0, and still more preferably 0.9. The change value of the lower limit of conditional expression (15) is preferably 0.2, more preferably 0.25, and still more preferably 0.3. From the above, it is more preferable to satisfy at least one of the following conditional expressions (15-1) to (15-3), for example.
0.1 <f12 / f3456 <1.5 (15-1)
0.2 <f12 / f3456 <1.0 (15-2)
0.3 <f12 / f3456 <0.9 (15-3)

The upper limit change value of conditional expression (16) is preferably −0.15, more preferably −0.2, and even more preferably −0.25. The lower limit change value of conditional expression (16) is preferably −2.5, more preferably −2.0, and even more preferably −1.5. From the above, it is more preferable that at least one of the following conditional expressions (16-1) to (16-3) is satisfied, for example.
−2.5 <(R5f + R5r) / (R5f−R5r) <− 0.1 (16-1)
−2.0 <(R5f + R5r) / (R5f−R5r) <− 0.15 (16-2)
−1.5 <(R5f + R5r) / (R5f−R5r) <− 0.2 (16-3)

The change value of the upper limit of conditional expression (17) is preferably 2.5, more preferably 2.0, and even more preferably 1.5. The change value of the lower limit of conditional expression (17) is preferably 0.4, more preferably 0.6, and even more preferably 0.8. From the above, it is more preferable to satisfy at least one of the following conditional expressions (17-1) to (17-3), for example.
0.4 <f2 / f <2.5 (17-1)
0.6 <f2 / f <2.0 (17-2)
0.8 <f2 / f <1.5 (17-3)

The change value of the upper limit of conditional expression (18) is preferably 2.5, more preferably 2.0, and even more preferably 1.5. The change value of the lower limit of conditional expression (18) is preferably 0.4, more preferably 0.6, and even more preferably 0.7. From the above, it is more preferable that at least one of the following conditional expressions (18-1) to (18-3) is satisfied, for example.
0.4 <(D3 + Db23) / f <2.5 (18-1)
0.6 <(D3 + Db23) / f <2.0 (18-2)
0.7 <(D3 + Db23) / f <1.5 (18-3)

The upper limit change value of conditional expression (19) is preferably −0.4, more preferably −0.6, and even more preferably −0.8. The lower limit change value of conditional expression (19) is preferably −2.5, more preferably −2.0, and even more preferably −1.5. From the above, it is more preferable that at least one of the following conditional expressions (19-1) to (19-3) is satisfied, for example.
−2.5 <f1 / f2 <−0.4 (19-1)
−2.0 <f1 / f2 <−0.6 (19-2)
−1.5 <f1 / f2 <−0.8 (19-3)

  The upper limit change value of conditional expression (21) is preferably 2.5, more preferably 2.0, even more preferably 1.5, and even more preferably 1.0. Even more preferable. The lower limit change value of conditional expression (21) is preferably 0.25, more preferably 0.3, and still more preferably 0.35.

The lower limit change value of conditional expression (22) is preferably 1.08, more preferably 1.12 and even more preferably 1.18. An upper limit may be added to the conditional expression (22), and the upper limit is preferably set to 5.0, whereby the air gap between the first lens L1 and the second lens L2 and the center thickness of the second lens L2 are set. It becomes easy to suppress, and the lens system can be easily downsized. The upper limit change value added to conditional expression (22) is preferably 3.0, more preferably 2.0, and even more preferably 1.8. From the above, it is more preferable that at least one of the following conditional expressions (22-1) to (22-5) is satisfied, for example.
1.0 <(Db12 + D3) / f <5.0 (22-1)
1.0 <(Db12 + D3) / f <3.0 (22-2)
1.08 <(Db12 + D3) / f <2.0 (22-3)
1.12 <(Db12 + D3) / f <1.8 (22-4)
1.18 <(Db12 + D3) / f <3.0 (22-5)

The lower limit change value of conditional expression (23) is preferably 1.7, more preferably 1.9, and even more preferably 2.0. An upper limit may be added to conditional expression (23), and the upper limit is preferably set to 10.0. This makes it easy to increase the combined power of the third lens L3 to the fifth lens L5, and spherical aberration. Astigmatism can be easily corrected. The upper limit change value added to the conditional expression (23) is preferably 7.0, more preferably 5.0, still more preferably 4.0, and 3.5. Even more preferred. From the above, it is more preferable that at least one of the following conditional expressions (23-1) to (23-4) is satisfied, for example.
1.6 <f3456 / f <10.0 (23-1)
1.7 <f3456 / f <7.0 (23-2)
1.9 <f3456 / f <4.0 (23-3)
2.0 <f3456 / f <3.5 (23-4)

The lower limit change value of conditional expression (24) is preferably −3.8, more preferably −3.5, and even more preferably −3.0. An upper limit may be added to conditional expression (24), and the upper limit is preferably set to −0.1. This makes it possible to prevent the image side surface of the sixth lens L6 from being concave and to prevent the absolute value of its radius of curvature from becoming too small, and to easily prevent the angle at which the peripheral rays are incident on the image sensor. It becomes. The upper limit change value added to the conditional expression (24) is preferably −0.3, more preferably −0.5, and even more preferably −0.6. From the above, it is more preferable that at least one of the following conditional expressions (24-1) to (24-4) is satisfied, for example.
−4.0 <(R6f + R6r) / (R6f−R6r) <− 0.1 (24-1)
−3.8 <(R6f + R6r) / (R6f−R6r) <− 0.3 (24-2)
−3.5 <(R6f + R6r) / (R6f−R6r) <− 0.5 (24-3)
−3.0 <(R6f + R6r) / (R6f−R6r) <− 0.6 (24-4)

  When the Abbe number of the material of the first lens L1 with respect to the d-line is νd1, νd1 is preferably larger than 40. This makes it easy to satisfactorily correct axial chromatic aberration and magnification chromatic aberration. νd1 is more preferably greater than 45, and even more preferably greater than 50.

  When the Abbe number of the material of the second lens L2 with respect to the d-line is νd2, νd2 is preferably larger than 30, thereby facilitating good correction of axial chromatic aberration. νd2 is more preferably greater than 35, and even more preferably greater than 38. Further, νd2 is preferably smaller than 60, which makes it easy to reduce the cost of the material of the second lens L2 and to easily correct the chromatic aberration of magnification. νd2 is more preferably less than 55, and even more preferably less than 50.

  νd1 / νd2 is preferably 1.0 or more. As a result, it becomes easy to increase the Abbe number of the first lens L1, and it becomes easy to correct axial chromatic aberration or to prevent the Abbe number of the material of the second lens L2 from becoming too large. Correction of chromatic aberration of magnification becomes easy. Further, νd1 / νd2 is preferably 1.6 or less. As a result, it is easy to suppress the Abbe number of the material of the second lens L2 from becoming too small, and axial chromatic aberration can be easily corrected.

When the Abbe number of the material of the third lens L3 with respect to the d-line is νd3, νd3 is preferably smaller than 27, thereby facilitating correction of axial chromatic aberration. νd3 is more preferably less than 26, even more preferably less than 25, and even more preferably less than 24. Further, νd3 is preferably larger than 19, which makes it easy to reduce the cost of the material of the third lens L3 and to make the lens system inexpensive. More preferably, νd3 is greater than 20. From the above, it is more preferable to satisfy at least one of the following conditional expressions (20-1) to (20-8), for example.
νd3 <27 (20-1)
νd3 <26 (20-2)
νd3 <25 (20-3)
νd3 <24 (20-4)
19 <νd3 <27 (20-5)
19 <νd3 <26 (20-6)
19 <νd3 <25 (20-7)
20 <νd3 <24 (20-8)

  When the Abbe number of the material of the fourth lens L4 with respect to the d-line is νd4, νd4 is preferably larger than 40, which facilitates correction of axial chromatic aberration and lateral chromatic aberration. νd4 is more preferably greater than 45, and even more preferably greater than 50. Further, νd4 is preferably smaller than 70, which makes it easy to reduce the cost of the material of the fourth lens L4 and to make the lens system inexpensive. νd4 is more preferably less than 65, and even more preferably less than 60.

  When the Abbe number of the material of the fifth lens L5 with respect to the d-line is νd5, νd5 is preferably larger than 40, which facilitates correction of axial chromatic aberration and lateral chromatic aberration. νd5 is more preferably greater than 45, and even more preferably greater than 50. Further, νd5 is preferably smaller than 70, which makes it easy to reduce the cost of the material of the fifth lens L5 and to make the lens system inexpensive. νd5 is more preferably less than 65, and even more preferably less than 60.

  When the Abbe number of the material of the sixth lens L6 with respect to the d-line is νd6, νd6 is preferably smaller than 27, which facilitates correction of axial chromatic aberration. νd6 is more preferably less than 26, and even more preferably less than 25. Further, νd6 is preferably larger than 19, which makes it easy to reduce the cost of the material of the sixth lens L6 and to make the lens system inexpensive.

  When the refractive index of the material of the first lens L1 with respect to the d-line is Nd1, Nd1 is preferably larger than 1.5. This makes it easy to increase the refractive index of the first lens L1, and the wide angle of the lens system. It becomes easy. Nd1 is more preferably greater than 1.51, and even more preferably greater than 1.55. Nd1 is preferably smaller than 1.85, which makes it easy to make the material of the first lens L1 inexpensive. Nd1 is more preferably less than 1.82, and even more preferably less than 1.80.

  When the refractive index for the d-line of the material of the second lens L2 is Nd2, Nd2 is preferably larger than 1.70, which facilitates correction of field curvature. Nd2 is more preferably greater than 1.72, and even more preferably greater than 1.75. Further, Nd2 is preferably smaller than 1.95, which makes it easy to make the material of the second lens L2 inexpensive. More preferably, Nd2 is less than 1.90.

  The object side surface of the first lens L1 is preferably a convex surface. Since the first lens L1 is a negative lens, when the object-side surface is a convex surface, the first lens L1 is a meniscus lens. Distortion can be easily corrected by using the first lens L1 as a meniscus lens having a convex surface on the object side.

  The image side surface of the first lens L1 is preferably a concave surface. This facilitates widening of the angle.

  The object side surface of the second lens L2 is preferably a convex surface. As a result, it is easy to increase the power of the second lens L2, and it is easy to correct astigmatism.

  The image-side surface of the second lens L2 is preferably a convex surface. As a result, it is easy to increase the power of the second lens L2, and it is easy to correct astigmatism.

  The second lens L2 is preferably a biconvex lens. As a result, it is easy to increase the power of the second lens L2, and it is easy to correct astigmatism.

  The second lens L2 is preferably a lens in which the absolute value of the curvature radius of the object side surface is larger than the absolute value of the curvature radius of the image side surface. This facilitates distortion correction.

  The object side surface of the third lens L3 is preferably a concave surface. Thereby, it becomes easy to increase the power of the third lens L3, and correction of axial chromatic aberration is facilitated.

  The image side surface of the third lens L3 is preferably a concave surface. Thereby, it becomes easy to increase the power of the third lens L3, and correction of axial chromatic aberration is facilitated.

  The third lens L3 is preferably a biconcave lens. Thereby, it becomes easy to increase the power of the third lens L3, and correction of axial chromatic aberration is facilitated.

  The third lens L3 may be a lens in which the absolute value of the radius of curvature of the object side surface is smaller than the absolute value of the radius of curvature of the image side surface, thereby facilitating correction of astigmatism.

  The third lens L3 may be a lens in which the absolute value of the curvature radius of the object-side surface is larger than the absolute value of the curvature radius of the image-side surface, and thereby the third lens L3 and the fourth lens L4 cooperate. This makes it easy to correct axial chromatic aberration.

  The object side surface of the fourth lens L4 is preferably a convex surface. This makes it easy to increase the power of the fourth lens L4, and it is easy to correct axial chromatic aberration by causing the third lens L3 and the fourth lens L4 to cooperate.

  The image-side surface of the fourth lens L4 is preferably a convex surface. This facilitates correction of astigmatism.

  The fourth lens L4 is preferably a biconvex lens. This makes it easy to increase the power of the fourth lens L4, and it is easy to correct axial chromatic aberration by causing the third lens L3 and the fourth lens L4 to cooperate.

  The object side surface of the fifth lens L5 is preferably a convex surface. As a result, it becomes easy to increase the power of the fifth lens L5, and it becomes easy to suppress an increase in the angle at which the peripheral rays are incident on the imaging device, and it is easy to suppress shading.

  The image side surface of the fifth lens L5 may be a convex surface or a flat surface. By making the image side surface of the fifth lens L5 convex or flat, it becomes easier to suppress the angle at which the peripheral rays are incident on the image sensor than when the concave surface is used, and shading can be easily suppressed. It becomes.

  The image side surface of the fifth lens L5 may be a concave surface. By making the image side surface of the fifth lens L5 concave, it is easy to correct field curvature.

  The fifth lens L5 may be a biconvex lens or a planoconvex lens with a convex surface facing the object side. By making the fifth lens L5 a biconvex lens or a plano-convex lens having a convex surface facing the object side, it becomes easy to increase the power of the fifth lens L5, and the angle at which the peripheral rays are incident on the imaging device is increased. It becomes easy to suppress, and it becomes easy to suppress shading.

  The fifth lens L5 may be a meniscus lens having a convex surface facing the object side. By using the fifth lens L5 as a meniscus lens having a convex surface directed toward the object side, it becomes easy to correct field curvature.

  The object side surface of the sixth lens L6 is preferably a concave surface. Thereby, it becomes easy to increase the power of the sixth lens L6, and it becomes easy to correct the chromatic aberration of magnification.

  The image side surface of the sixth lens L6 may be a convex surface or a flat surface. By making the image side surface of the sixth lens L6 a convex surface or a flat surface, it is easy to suppress an increase in the angle at which the peripheral rays are incident on the image sensor.

  The image side surface of the sixth lens L6 may be a concave surface. By making the image side surface of the sixth lens L6 concave, it is easy to correct curvature of field and distortion.

  The sixth lens L6 may be a negative meniscus lens or a plano-concave lens having a concave surface facing the object side. By making the sixth lens L6 a negative meniscus lens or a plano-concave lens having a concave surface directed toward the object side, it becomes easy to suppress an increase in the angle at which the peripheral rays are incident on the image sensor.

  The sixth lens L6 may be a biconcave lens. By making the sixth lens L6 a biconcave lens, it becomes easy to correct chromatic aberration of magnification and to correct curvature of field.

  The absolute value of the radius of curvature of the object side surface of the sixth lens L6 is preferably smaller than the absolute value of the radius of curvature of the image side surface. Thereby, it becomes easy to suppress an increase in the angle at which the peripheral rays are incident on the image sensor.

  Any surface of each of the first lens L1 to the sixth lens L6 may be an aspherical surface. Thereby, it becomes easy to correct various aberrations satisfactorily.

  The object side surface of the third lens L3 is preferably an aspherical surface. The surface on the object side of the third lens L3 may have a negative power near the optical axis, and may have a shape having a stronger negative power at the effective diameter end than in the vicinity of the optical axis. By making the object side surface of the third lens L3 into such a shape, it becomes easy to satisfactorily correct spherical aberration.

  The object side surface of the third lens L3 may have an aspheric shape having positive power near the optical axis and negative power at the effective diameter end. By making the object side surface of the third lens L3 into such a shape, it becomes easy to satisfactorily correct spherical aberration.

  The image side surface of the third lens L3 is preferably an aspherical surface. It is preferable that the image side surface of the third lens L3 has a negative power near the optical axis, and has a shape in which the negative power is weaker at the effective diameter end than in the vicinity of the optical axis. By making the image side surface of the third lens L3 such a shape, it becomes easy to reduce the size of the lens system, or to easily correct astigmatism and coma.

  The object side surface of the fourth lens L4 is preferably an aspherical surface. The object side surface of the fourth lens L4 preferably has a positive power near the optical axis, and has a shape with a weak positive power at the effective diameter end as compared with the vicinity of the optical axis. By making the object side surface of the fourth lens L4 in this shape, it becomes easy to satisfactorily correct spherical aberration.

  The image-side surface of the fourth lens L4 is preferably an aspherical surface. It is preferable that the image side surface of the fourth lens L4 has a positive power near the optical axis, and has a shape with a stronger positive power at the effective diameter end than in the vicinity of the optical axis. By making the object side surface of the fourth lens L4 in such a shape, it becomes easy to satisfactorily correct astigmatism.

  The object side surface of the fifth lens L5 is preferably an aspherical surface. It is preferable that the object side surface of the fifth lens L5 has a positive power near the optical axis and has a shape with a weak positive power at the effective diameter end as compared with the vicinity of the optical axis. By making the object side surface of the fifth lens L5 into such a shape, it becomes easy to satisfactorily correct spherical aberration and astigmatism.

  The image-side surface of the fifth lens L5 is preferably an aspherical surface. It is preferable that the image side surface of the fifth lens L5 has a positive power near the optical axis and has a shape with a weak positive power at the effective diameter end as compared with the vicinity of the optical axis. By making the image side surface of the fifth lens L5 into such a shape, it becomes easy to satisfactorily correct spherical aberration and astigmatism.

  The object side surface of the sixth lens L6 is preferably an aspherical surface. It is preferable that the object side surface of the sixth lens L6 has a negative power near the optical axis, and has a shape with a strong negative power at the effective diameter end as compared with the vicinity of the optical axis. By making the object side surface of the sixth lens L6 into such a shape, it becomes easy to satisfactorily correct spherical aberration and astigmatism.

  The image side surface of the sixth lens L6 is preferably an aspherical surface. The image side surface of the sixth lens L6 may have a positive power near the optical axis, and may have a shape where the positive power is weaker at the effective diameter end than in the vicinity of the optical axis. By making the image side surface of the sixth lens L6 into such a shape, it becomes easy to satisfactorily correct spherical aberration and astigmatism. Alternatively, the image side surface of the sixth lens L6 may have a negative power near the optical axis, and a shape having a stronger negative power than the vicinity of the optical axis at the effective diameter end. By making the image side surface of the sixth lens L6 into such a shape, it becomes easy to satisfactorily correct spherical aberration and astigmatism.

  Note that the “effective diameter of the surface” is a circle consisting of the outermost point in the radial direction (the point farthest from the optical axis) when the point where all the rays that contribute to image formation intersect with the lens surface is considered. It means the diameter, and “effective diameter end” means the outermost point. For example, when the lens system is used in combination with an imaging device, the effective diameter can be determined based on the size of the imaging surface of the imaging device. In the case of a system in which the imaging surface is rectangular and the intersection of the two diagonal lines passes through the optical axis, for example, the effective diameter can be determined by considering 1/2 of the diagonal line as the maximum image height.

  Also, the power at a point on the surface other than on the optical axis is considered to be a normal to the surface passing through that point, and the point where the normal and the optical axis intersect (hereinafter referred to as the intersection of the normal and the optical axis) It is defined as either on the object side or on the image side compared to the point where the surface and the optical axis intersect (hereinafter referred to as the intersection of the surface and the optical axis). When the lens surface is on the object side and the intersection of the normal and the optical axis is closer to the image side than the intersection of the surface and the optical axis, the power at that point is positive, and the intersection of the normal and the optical axis is the surface and the optical axis. In the case of the object side from the intersection point, the power at that point is negative. If the lens surface is on the image side and the intersection of the normal and the optical axis is closer to the object side than the intersection of the surface and the optical axis, the power at that point is positive, and the intersection of the normal and the optical axis is the surface and the optical axis. In the case of the image side from the intersection point, the power at that point is negative.

  In the example shown in FIG. 1, all the lenses are single lenses, and thus all the lenses constituting the lens system may not be cemented. For example, when used as an in-vehicle lens, the lens system is required to have high heat resistance and environmental resistance. When using a cemented lens, depending on the conditions, a special bonding agent may be used to increase heat resistance and environmental resistance, and processing that increases environmental resistance may be required, resulting in high costs. . In such a case, all of the first lens L1 to the sixth lens L6 may be single lenses.

  However, in the case where the above-mentioned point of the bonding agent is not a problem, it is possible to reduce the axial misalignment between the lenses by bonding the lenses and contribute to ensuring good performance. You may comprise so that a lens may be included. For example, the third lens L3 and the fourth lens L4 may be cemented, the fifth lens L5 and the sixth lens L6 may be cemented, or the two lenses of the cemented lens may be included at the same time.

  In the imaging lens 1 of the present invention, it is preferable that the aperture stop St, which is a diaphragm for determining the F value (F number) of the lens system, is disposed on the object side from the image side surface of the fourth lens L4. This makes it easy to reduce the aperture diameter of the first lens L1, and facilitates downsizing of the lens system. For example, when the imaging lens 1 is used in an in-vehicle camera, the portion exposed to the outside of the lens is required to be small so as not to impair the appearance of the car. Furthermore, by disposing the aperture stop St closer to the object side than the image-side surface of the fourth lens L4, it is easy to suppress an increase in the angle at which peripheral rays are incident on the image sensor, and it is easy to suppress shading. It becomes.

  More preferably, the aperture stop St is disposed closer to the object side than the image side surface of the third lens L3. This makes it easier to further reduce the aperture diameter of the first lens L1. In addition, it is preferable that the aperture stop St is disposed on the image side with respect to the object side surface of the second lens L2. This facilitates reducing the lens diameter of the fifth lens L5. In particular, the aperture stop St is preferably disposed between the object-side surface of the third lens L3 and the object-side surface of the second lens L2. Thereby, it becomes easy to balance the diameters of the lenses from the first lens L1 to the fifth lens L5, and it becomes easy to reduce the diameter of the entire lens.

  The material constituting the first lens L1 is preferably glass. For example, when the imaging lens 1 is used in a harsh environment such as an in-vehicle camera or a surveillance camera, the first lens L1 disposed closest to the object side is resistant to surface deterioration due to wind and rain and temperature changes due to direct sunlight. Furthermore, it is required to use materials that are resistant to chemicals such as oils and fats, that is, water resistance, weather resistance, acid resistance, chemical resistance, etc., and that materials that are hard and hard to break are required. Sometimes. By making the material of the 1st lens L1 into glass, it becomes possible to satisfy | fill these requests. Moreover, you may use transparent ceramics as a material of the 1st lens L1.

  In order to produce an optical system with good environmental resistance, it is preferable that the material of all lenses is glass. For example, when the imaging lens 1 is used for a monitoring camera or a vehicle-mounted camera, it is used under various conditions such as a wide temperature range from high temperature to low temperature, such as from outside air in a cold region to the interior of a tropical summer, and high humidity. there is a possibility. In order to produce an optical system that is strong against them, it is preferable that the material of all the lenses is glass.

  The material of the second lens L2 is preferably glass. By making the second lens L2 a glass lens, it becomes easy to increase the refractive index of the material of the second lens L2, and correction of field curvature becomes easy.

  In addition, you may use a plastic for the material of each lens of the 1st lens L1-the 6th lens L6. In particular, it is preferable to use plastic as the material of any one of the third lens L3 to the sixth lens L6, or any combination of lenses. As a result, if the lens made of plastic is an aspheric lens, the aspheric lens can be manufactured inexpensively and with high accuracy, so that various aberrations can be corrected satisfactorily while suppressing the cost of the lens. Becomes easy.

  As the plastic material, for example, acrylic, polyolefin-based material, polycarbonate-based material, epoxy resin, PET (Polyethylene terephthalate), PES (Poly Ether Sulphone), polyester-based material, or the like can be used. Further, a so-called nanocomposite material in which particles smaller than the wavelength of light are mixed in plastic may be used.

  Depending on the application of the imaging lens 1, a filter that transmits or reflects a specific wavelength region such as a UV filter or an IR filter may be inserted between the lens system and the imaging device 5 or between each lens. . Alternatively, a coating having the same characteristics as the filter may be applied to the lens surface of any lens. Alternatively, a material that absorbs ultraviolet light, blue light, infrared light, or the like may be used as a material of any lens.

  In addition, since the light flux that passes outside the effective diameter between the lenses becomes stray light and reaches the image plane and may become a ghost, it is preferable to provide a light shielding member that shields the stray light as necessary. As the light shielding member, for example, an opaque paint or an opaque plate material applied to a portion outside the effective diameter of the lens may be used. The light shielding member may be disposed between any lenses as necessary. Alternatively, a hood that shields stray light from the first lens L1 to the object side may be disposed. As an example, FIG. 1 shows an example in which the light shielding members 11 and 12 are provided outside the effective diameters of the image-side surfaces of the first lens L1 and the third lens L3. The location where the light shielding member is provided is not limited to the example shown in FIG. 1 and may be disposed between other lenses or between the lenses.

  Further, a member such as a diaphragm that shields the peripheral light beam may be arranged between the lenses so long as the peripheral light amount ratio has no practical problem. Such a member can improve the image quality in the periphery of the imaging region.

  Arbitrary combinations are possible for the preferable configurations described above, and it is preferable that they be selectively adopted as appropriate according to the specifications required for the imaging lens 1. By appropriately selecting a preferred configuration, it is possible to realize an optical system that can cope with better optical performance and higher specifications.

[Numerical example of imaging lens]
Next, numerical examples of the imaging lens of the present invention will be described. Lens sectional views of the imaging lenses of Examples 1 to 20 are shown in FIGS. 2 to 21, the left side of the figure is the object side, the right side is the image side, and the aperture stop St and the optical member PP are also shown. The aperture stop St in each figure does not indicate the shape or size, but indicates the position on the optical axis Z. In each embodiment, symbols Ri and Di (i = 1, 2, 3,...) In the lens cross-sectional view correspond to Ri and Di of lens data described below.

  Tables 1 to 20 show lens data of the imaging lenses of Examples 1 to 20, respectively. The upper left of each table shows basic lens data, the upper right shows various data, and the lower shows aspherical data.

  In the basic lens data, the column of Si indicates the i-th (i = 1, 2, 3,...) Surface number that increases sequentially toward the image side with the object-side surface of the most object-side component as the first. , Ri column indicates the radius of curvature of the i-th surface, and Di column indicates the surface spacing on the optical axis Z between the i-th surface and the i + 1-th surface. The sign of the radius of curvature is positive when the surface shape is convex on the object side and negative when the surface shape is convex on the image side. The column Ndj corresponds to the d-line (wavelength 587.6 nm) of the j-th (j = 1, 2, 3,...) Optical element that sequentially increases toward the image side with the most optical element on the object side as the first. The refractive index is shown, and the column νdj shows the Abbe number of the j-th optical element with respect to the d-line. The basic lens data includes the aperture stop St and the optical member PP. In the surface number column of the surface corresponding to the aperture stop St and the image surface Sim, the words (St) and (IMG) are described together with the surface number.

In the basic lens data, the surface number of the aspheric surface is marked with *, and the value of the paraxial curvature radius is shown as the curvature radius of the aspheric surface. The aspheric coefficient table shows the surface number of the aspheric surface and the aspheric coefficient related to each aspheric surface. The numerical value “E−n” (n: integer) of the aspheric coefficient means “× 10 ⁻ⁿ ”. The aspheric coefficient is a value of each coefficient K, RBm (m = 3, 4, 5,... 10) in the aspheric expression represented by the following expression.
However,
Zd: Depth of aspheric surface (length of perpendicular drawn from a point on the aspherical surface of height Y to a plane perpendicular to the optical axis where the aspherical vertex contacts)
Y: Height (distance from the optical axis to the lens surface)
C: Paraxial curvature K, RBm: Aspheric coefficient (m = 3, 4, 5,... 10)

  In various data, L (in Air) is the distance on the optical axis Z from the object-side surface of the first lens L1 to the image plane Sim (the back focus is the air equivalent length), and Bf (in Air) is the most image side. The distance on the optical axis Z from the image side surface of the lens to the image plane Sim (corresponding to back focus in terms of air length), f is the focal length of the entire system, f1 is the focal length of the first lens L1, and f2 Is the focal length of the second lens L2, f3 is the focal length of the third lens L3, f4 is the focal length of the fourth lens L4, f5 is the focal length of the fifth lens L5, f6 is the focal length of the sixth lens L6, and f12. Is the combined focal length of the first lens L1 and the second lens L2, f56 is the combined focal length of the fifth lens L5 and the sixth lens L6, and f3456 is the combined focal length of the third lens L3 to the sixth lens L6. is there.

  In the table of this specification, numerical values rounded by a predetermined digit are described. Here, “mm” is used as the unit of length for each numerical value. However, this is only an example, and the optical system can be used even with proportional enlargement or reduction, so use another appropriate unit. You can also.

  In the imaging lenses of Examples 1 to 3 and 10, the first lens L1, the second lens L2, and the sixth lens L6 are glass spherical lenses, and the third lens L3 to the fifth lens L5 are plastic lenses. In the imaging lenses of Examples 4 to 9 and 11 to 20, the first lens L1 and the second lens L2 are glass spherical lenses, and the third lens L3 to the sixth lens L6 are plastic lenses. In the basic lens data, the name of the glass lens is described in the glass column for the glass lens, but other glass types may be used as long as they have the same characteristics with respect to the refractive index and the Abbe number.

  For example, what is described as S-YGH51 in the glass column of the basic lens data is S-YGH51 manufactured by OHARA, but glass materials of other companies having equivalent characteristics may be used. For example, instead of this, HOYA TAC6 manufactured by Sumitomo Chemical Co., Ltd., K-LASKN1 manufactured by Sumita Co., Ltd., H-LAK53A manufactured by Chengdu Komyo Co., Ltd., etc. may be used. Similarly, HOYA TAF1, M-TAF1, Sumita K-LAFK50, K-LASFN7, Chengdu Komyo H-ZLAF50B, Schott N-LAF34, etc. are used instead of Ohara S-LAH66. May be. Instead of S-LAH55V manufactured by OHARA, TAFD5F manufactured by HOYA, K-LASFN8 manufactured by Sumita Co., Ltd., H-ZLAF55A manufactured by Chengdu Komyo Co., etc. may be used. Instead of OHARA S-BAL35, HOYA BACD5, Sumita K-SK5, Chengdu Komyo H-ZK3, etc. may be used. Instead of OHARA S-LAH65V, HOYA TAF3, Sumita K-LASFN6, Chengdu Komei H-ZLAF50D, etc. may be used. Instead of HOYA BSC7, Ohara S-BSL7, Sumita K-BK7, Chengdu Komyo H-K9L, Schott N-BK7, etc. may be used. Instead of OHARA S-LAL8, HOYA LAC8, Sumita K-LAK8, Chengdu Komyo H-LAK7A, etc. may be used. Instead of M-TAFD51 manufactured by HOYA, Q-LASFH59S manufactured by Hikari Glass may be used. Instead of S-LAH58 manufactured by OHARA, TAFD30 manufactured by HOYA, K-LASFN17 manufactured by Sumita Co., Ltd., H-ZLAF68 manufactured by Chengdu Komyo Co., etc. may be used.

  For the imaging lenses of Examples 1 to 20, values corresponding to the conditional expressions (1) to (12) are shown in Table 21, and values corresponding to the conditional expressions (13) to (24) are shown in Table 22. In Examples 1 to 20, the d-line is used as a reference wavelength, and Tables 21 and 22 show values at this reference wavelength.

  The aberration diagrams of the imaging lenses according to Examples 1 to 20 are shown in FIGS. 22 to 41, respectively. 22 to 41, for each example, in order from the left, aberration diagrams of spherical aberration, astigmatism, distortion (distortion aberration), and chromatic aberration of magnification (chromatic aberration of magnification) are shown. Fno. Of spherical aberration diagram. Means F number, and ω in other aberration diagrams means a half angle of view in a state in which an object at infinity is in focus. Each aberration diagram shows aberrations with the d-line (587.56 nm) as the reference wavelength, while the spherical aberration diagram shows the F-line (wavelength 486.13 nm), C-line (wavelength 656.27 nm), and s-line ( (Wavelength 852.11 nm), the aberration for the sine condition violation amount is also shown, and the chromatic aberration diagram for the magnification shows the aberration for the F-line, C-line, and s-line.

  As can be seen from the above data, the imaging lenses of Examples 1 to 20 are small and can be manufactured at low cost, and have an F number in the range of 1.60 to 2.00 and a small F number. The entire angle of view is in the range of 65 ° to 80 °, achieving a wide angle of view, and various aberrations including chromatic aberration are well corrected to provide high optical performance. These imaging lenses can be suitably used for surveillance cameras, in-vehicle cameras for taking images of the front, side, rear, etc. of automobiles.

[Embodiment of Imaging Device]
As a usage example, FIG. 42 illustrates a state in which an imaging apparatus including the imaging lens of the present embodiment is mounted on the automobile 100. In FIG. 42, an automobile 100 includes an on-vehicle camera 101 for imaging a blind spot range on the side surface on the passenger seat side, an on-vehicle camera 102 for imaging a blind spot range on the rear side of the automobile 100, and a rear surface of a rearview mirror. An in-vehicle camera 103 is attached and is used for photographing the same field of view as the driver. The vehicle exterior camera 101, the vehicle exterior camera 102, and the vehicle interior camera 103 are imaging devices according to the embodiment of the present invention. An imaging lens according to the embodiment of the present invention and an optical image formed by the imaging lens are used as electrical signals. An image sensor for conversion.

  Since the imaging lens according to the embodiment of the present invention has the above-described advantages, the outside cameras 101 and 102 and the inside camera 103 do not impair the appearance of the car, can be configured in a small size and at low cost, and have a wide image. It has corners and a good image can be obtained.

  In addition, you may make it display the image image | photographed with the imaging device provided with the imaging lens which concerns on embodiment of this invention on a mobile telephone. For example, an imaging device including the imaging lens according to the present embodiment may be mounted on a vehicle as a vehicle-mounted camera, the back and the periphery of the vehicle may be captured by the vehicle-mounted camera, and an image acquired by the shooting may be displayed on the display device. In such a case, in a car equipped with a car navigation system (hereinafter referred to as a car navigation system), the captured image may be displayed on the display device of the car navigation system. It is necessary to install a dedicated display device in the car. However, the display device is expensive. On the other hand, mobile phones in recent years are equipped with high-performance display devices such as being able to browse videos and Web. By using a mobile phone as a display device for a vehicle-mounted camera, it is not necessary to mount a dedicated display device even for a car that does not have a car navigation system. As a result, it is possible to mount a vehicle-mounted camera at a low cost. Become.

  Here, the image captured by the in-vehicle camera may be transmitted to the mobile phone by cable using a cable or the like, or may be transmitted to the mobile phone by radio such as infrared communication. In addition, the mobile phone and the operating state of the car are linked so that when the car's gear enters the back or the winker is taken out, the image of the in-vehicle camera is automatically displayed on the display device of the mobile phone. It may be.

  In addition, as a display device for displaying the image of the in-vehicle camera, not only a mobile phone but also a portable information terminal such as a PDA, a tablet terminal, a small personal computer, or a portable car navigation system can be used. Good.

  Moreover, you may use as a vehicle-mounted camera by fixing the mobile telephone (a smart phone is included) carrying the imaging lens of this invention to a motor vehicle. Since recent smartphones have the same processing capabilities as PCs, for example, the mobile phone camera can be used in the same way as an in-vehicle camera by fixing the mobile phone to the dashboard of an automobile and pointing the camera forward. Is possible. Note that a smart phone application may have a function of recognizing a white line or a road sign and issuing a warning. Moreover, it is good also as a system which points a camera at a driver | operator and warns at the time of dozing or looking aside. Moreover, it is good also as a part of the system which interlocks with a motor vehicle and operates a steering wheel. Since an automobile is left in a high temperature environment or a low temperature environment, a vehicle-mounted camera is required to have severe environmental resistance. When the imaging lens of the present invention is mounted on a mobile phone, the mobile phone goes out of the vehicle with the driver except when driving, so the environment resistance of the imaging lens can be relaxed, and an in-vehicle system is introduced at a low cost. It becomes possible.

  The present invention has been described with reference to the embodiments and examples. However, the present invention is not limited to the above embodiments and examples, and various modifications can be made. For example, the values of the radius of curvature, the surface spacing, the refractive index, the Abbe number, and the aspheric coefficient of each lens are not limited to the values shown in the above numerical examples, and can take other values.

  In the above embodiment, all the lenses are made of a homogeneous material, but a gradient index lens may be used. Further, in the above-described embodiments, there are some which are constituted by a refractive lens provided with an aspherical surface, but a diffractive optical element may be formed on one surface or a plurality of surfaces.

  Further, in the embodiment of the imaging apparatus, the example in which the present invention is applied to a vehicle-mounted camera has been described with reference to the drawings. However, the present invention is not limited to this application, and for example, a mobile terminal camera or a surveillance camera The present invention can also be applied.

DESCRIPTION OF SYMBOLS 1 Imaging lens 2 On-axis light beam 3, 4 Off-axis light beam 5 Imaging element 11, 12 Light-shielding member 100 Car 101, 102 Outside camera 103 In-vehicle camera L1 1st lens L2 2nd lens L3 3rd lens L4 4th lens L5 5th Lens L6 6th lens Pim Image point PP Optical member Sim Image surface St Aperture stop Z Optical axis

Claims (20)

In order from the object side, a first lens having a negative refractive power, a second lens having a positive refractive power, a third lens having a negative refractive power, a fourth lens having a positive refractive power, and a positive lens An imaging lens that substantially consists of six lenses including a fifth lens having a refractive power of 6 and a sixth lens having a negative refractive power and satisfies the following conditional expression.
Nd3 <1.7 (1)
Nd4 <1.6 (2)
Nd5 <1.6 (3)
Nd6 <1.89 (4)
However,
Nd3: refractive index of the third lens material with respect to the d-line Nd4: refractive index of the fourth lens material with respect to the d-line Nd5: refractive index of the fifth lens material with respect to the d-line Nd6: material of the sixth lens Refractive index for d-line The imaging lens according to claim 1 that satisfies the following conditional expression.
1.0 <(R1f + R1r) / (R1f−R1r) (5)
However,
R1f: paraxial radius of curvature of the object side surface of the first lens R1r: paraxial radius of curvature of the image side surface of the first lens The imaging lens according to claim 1 or 2, wherein the following conditional expression is satisfied.
0.3 <f4 / f5 (6)
However,
f4: focal length of the fourth lens f5: focal length of the fifth lens The imaging lens according to claim 1, wherein the following conditional expression is satisfied.
f5 / f <3.4 (7)
However,
f5: focal length of the fifth lens f: focal length of the entire system The imaging lens according to claim 1, wherein the following conditional expression is satisfied.
0.3 <f56 / f (8)
However,
f56: combined focal length of the fifth lens and the sixth lens f: focal length of the entire system The imaging lens according to claim 1, wherein the following conditional expression is satisfied.
0.17 <Db23 / f (9)
However,
Db23: air space on the optical axis of the second lens and the third lens f: focal length of the entire system The imaging lens according to claim 1, wherein the following conditional expression is satisfied.
0.0 <R1f / f (10)
However,
R1f: paraxial radius of curvature of the object side surface of the first lens f: focal length of the entire system The imaging lens according to claim 1, wherein the following conditional expression is satisfied.
−3.0 <f1 / f <−0.5 (11)
However,
f1: Focal length of the first lens f: Focal length of the entire system The imaging lens according to claim 1, wherein the following conditional expression is satisfied.
−0.15 <(R2f + R2r) / (R2f−R2r) (12)
However,
R2f: paraxial radius of curvature of the object side surface of the second lens R2r: paraxial radius of curvature of the image side surface of the second lens The imaging lens according to claim 1, wherein the following conditional expression is satisfied.
0.1 <f12 / f <4.0 (13)
However,
f12: combined focal length of the first lens and the second lens f: focal length of the entire system The imaging lens according to claim 1, wherein the following conditional expression is satisfied.
0.5 <f4 / f <5.0 (14)
However,
f4: focal length of the fourth lens f: focal length of the entire system The imaging lens according to claim 1, wherein the following conditional expression is satisfied.
0.1 <f12 / f3456 <2.0 (15)
However,
f12: Composite focal length of the first lens and the second lens f3456: Composite focal length from the third lens to the sixth lens The imaging lens according to claim 1, wherein the following conditional expression is satisfied.
−3.0 <(R5f + R5r) / (R5f−R5r) <− 0.1 (16)
However,
R5f: Paraxial radius of curvature of the object side surface of the fifth lens R5r: Paraxial radius of curvature of the image side surface of the fifth lens The imaging lens according to claim 1, wherein the following conditional expression is satisfied.
0.2 <f2 / f <3.0 (17)
However,
f2: focal length of the second lens f: focal length of the entire system The imaging lens according to claim 1, wherein the following conditional expression is satisfied.
0.2 <(D3 + Db23) / f <3.0 (18)
However,
D3: Center thickness of the second lens Db23: Air spacing on the optical axis of the second lens and the third lens f: Focal length of the entire system The imaging lens according to claim 1, wherein the following conditional expression is satisfied.
−3.0 <f1 / f2 <−0.2 (19)
However,
f1: Focal length of the first lens f2: Focal length of the second lens The imaging lens according to claim 1, wherein the following conditional expression is satisfied.
νd3 <30 (20)
However,
νd3: Abbe number of the third lens material with respect to the d-line   The imaging lens according to claim 1, wherein the fourth lens is a biconvex lens. The imaging lens according to claim 1, wherein the following conditional expression is satisfied.
0.2 <Db12 / f <3.0 (21)
However,
Db12: Air spacing on the optical axis of the first lens and the second lens f: Focal length of the entire system   An imaging device comprising the imaging lens according to claim 1.